Field of the Invention
The present invention relates to the structure of a secondary battery.
Description of Related Art
Alkaline secondary batteries and nonaqueous electrolyte secondary batteries are used as power sources of electric vehicles (EV) and hybrid electric vehicles (HEV, PHEV). When using such secondary batteries as automotive batteries for EV, HEV, PHEV, and the like, a high capacity and a high output power performance are required. Therefore, an assembled battery, in which a large number of secondary batteries are connected in series or in parallel, is used.
Each of these secondary batteries includes a battery case that is composed of a metal housing, which has an opening, and a sealing plate, which seals the opening. An electrode body and air electrolyte are disposed in the battery case. The electrode body includes a positive electrode plate, a negative electrode plate, and a separator. A positive electrode terminal and a negative electrode terminal are fixed to the sealing plate. The positive electrode terminal is electrically connected to the positive electrode plate through a positive electrode current collector. The negative electrode terminal is electrically connected to the negative electrode terminal through a negative electrode current collector.
Regarding a method of connecting a terminal to a current collector, for example, Japanese Published Unexamined Patent Application No. 2011-76867 (Patent Document 1) describes a technology for connecting a terminal to a current collector by forming a through-hole in the current collector, inserting a lower end portion of the terminal into the through-hole, and upsetting the lower end portion of the terminal.
Particularly good output power performance is required for secondary batteries used in hybrid electric vehicles (HEV, PHEV) and the like. Therefore, it is necessary to develop secondary batteries having, reduced internal resistance.